Measurement of phi meson parameters with CMD-2 detector at VEPP-2M collider

Akhmetshin, R.R. ; Aksenov, G.A. ; Anashkin, E.V. ; et al.
Phys.Lett.B 364 (1995) 199-206, 1995.
Inspire Record 406880 DOI 10.17182/hepdata.28437

Results of the measurement of the φ meson parameters with the general purpose detector CMD-2 at the upgraded e + e − collider VEPP-2M at Novosibirsk are presented. This is the first measurement of the four major φ decay modes in a single e + e − experiment. The results based on about 55,600 identified hadronic events are consistent with previous measurements, and have precision comparable to the current world average.

1 data table

No description provided.


Search for rare Phi decays in pi+ pi_ gamma final state

The CMD-2 collaboration Akhmetshin, R.R. ; Aksenov, G.A. ; Anashkin, E.V. ; et al.
Phys.Lett.B 415 (1997) 452-462, 1997.
Inspire Record 451091 DOI 10.17182/hepdata.41643

A search for phi radiative decays has been performed using a data sample of about 2.0 million phi decays collected by the CMD-2 detector at VEPP-2M collider in Novosibirsk. From the selected e+ e- -> pi+ pi- gamma events the following results were obtained: B(phi -> f0(980) gamma) < 1x10-4 for destructive and B(phi -> f0(980) gamma) < 7x10-4 for constructive interference with the Bremsstrahlung process respectively, B(phi -> gamma -> pi+ pi- gamma) < 3x10-5 for E of gamma > 20 MeV, B(phi -> rho gamma) < 7x10-4. From the selected e+ e- -> mu+ mu- gamma events B(phi -> mu+ mu- gamma) = (2.3+-1.0)x10-5 has been obtained for E of gamma> 20 MeV. The upper limit on the P,CP-violating decay eta -> pi+ pi- has also been placed: B(eta -> pi+ pi-) < 9x10-4 . All upper limits are at 90 % C.L.

1 data table

Only statistical errors are shown in the table.


Study of dynamics of Phi --> pi+ pi- pi0 decay with CMD-2 detector.

Akhmetshin, R.R ; Aksenov, G.A ; Anashkin, E.V ; et al.
Phys.Lett.B 434 (1998) 426-436, 1998.
Inspire Record 480170 DOI 10.17182/hepdata.28172

A study of the φ → π + π − π 0 decay mode has been performed using a data sample of about 2.0 million φ decays collected by the CMD-2 detector at VEPP-2M collider in Novosibirsk. The following parameters of the φ -meson have been measured: Br ( φ → π + π − π 0 )=0.145±0.009±0.003 and δ φ − ω =162±17°. The analysis of the Dalitz plot showed the dominance of the φ → ρπ intermediate mechanism, the limits for the ratio of the direct amplitude of φ →3 π to that of φ → ρπ are −0.16< a 1 <0.11 at 90% C.L. The upper limits for the probabilities of the decay modes φ → π + π − η and direct φ → ργγ have been found for the first time: Br ( φ → π + π − η )<3×10 −4 and Br ( φ → ργγ )<5×10 −4 at 90% C.L.

1 data table

No description provided.


a_1(1260) dominance in the process e+e- \to 4\pi at energies 1.05--1.38 GeV

The CMD-2 collaboration Akhmetshin, R.R. ; Anashkin, E.V. ; Arpagaus, M. ; et al.
Phys.Lett.B 466 (1999) 392-402, 1999.
Inspire Record 483994 DOI 10.17182/hepdata.50145

First results of the study of the process e+e- \to 4\pi by the CMD-2 collaboration at VEPP-2M are presented for the energy range 1.05--1.38 GeV. Using an integrated luminosity of 5.8 pb^{-1}, energy dependence of the processes e+e- \to \pi^+\pi^- 2\pi^0 and e+e- \to 2\pi^+ 2\pi^- has been measured. Analysis of the differential distributions demonstrates the dominance of the a_1\pi and \omega\pi intermediate states. Upper limits for the contributions of other alternative mechanisms are also placed.

3 data tables

Energy dependence of the cross section for the 2PI+ 2PI- final state. Statistical errors only.

Energy dependence of the cross section for the PI+ PI- 2PI0 final state. Statistical errors only.

Energy dependence of the cross section for the OMEGA PI0 final state. Statistical errors only.


Experiments at VEPP-2M with SND detector

The SND collaboration Achasov, M.N. ; Aulchenko, V.M. ; Baru, S.E. ; et al.
BINP-98-65, 1998.
Inspire Record 476386 DOI 10.17182/hepdata.50374

Short overview of experiments with SND detector at VEPP-2M e^+e^- collider in the energy range 2E = 400 - 1400 MeV and preliminary results of data analysis are presented.

4 data tables

No description provided.

No description provided.

No description provided.

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Investigation of the $e^+e^- \to \omega \pi^0 \to \pi^0 \pi^0 \gamma$ reaction in the energy domain near the $\phi$-meson

Achasov, M.N. ; Aulchenko, V.M. ; Berdyugin, A.V. ; et al.
Nucl.Phys.B 569 (2000) 158-182, 2000.
Inspire Record 503946 DOI 10.17182/hepdata.41517

The $e^+e^- \to \omega \pi^0 \to \pi^0 \pi^0 \gamma$ process was investigated in the SND experiment at the VEPP-2M collider. A narrow energy interval near the $\phi$-meson was scanned. The observed cross-section reveals, at the level of three standard deviation, the interference effect caused by $\phi \to \pi^0\pi^0\gamma$ decay. The cross-section parameters, as well as the real and imaginary parts of the $\phi$-meson related amplitude, were measured.

2 data tables

Only statistical errors are presented. Cross section times branching ratio.

Cross section corrected for the branching ratio OMEGA --> PI0 GAMMA, at the PHI meson. In the range 984 to 1060 MeV the E+ E- --> OMEGA PI0 cross section can be approximated as (7.5 +- 0.9) + (0.06 +- 0.03) (SQRT(S)-M(PHI)) NB where M(PHI) = 1019.4 MeV and S is in MeV**2.


The process e+ e- --> omega pi0 --> pi0 pi0 gamma up to 1.4-GeV.

Achasov, M.N. ; Beloborodov, K.I. ; Berdyugin, A.V. ; et al.
Phys.Lett.B 486 (2000) 29-34, 2000.
Inspire Record 527752 DOI 10.17182/hepdata.41747

The cross section of the $e^+e^-\to\omega\pi^0\to\pi^0\pi^0\gamma$ reaction was measured by the SND detector at VEPP-2M $e^+e^-$ collider in the energy range from threshold up to 1.4 GeV. Results of the cross section fitting by the sum of $\rho$, $\rho^{\prime}$ and $\rho^{\prime\prime}$ contributions are presented.

1 data table

Only statistical errors are presented.


Observation of the phi to pi+pi-pi+pi- Decay

The CMD-2 collaboration Akhmetshin, R.R. ; Anashkin, E.V. ; Arpagaus, M. ; et al.
Phys.Lett.B 491 (2000) 81-89, 2000.
Inspire Record 531667 DOI 10.17182/hepdata.41735

Using 11.6 pb^{-1} of data collected in the energy range 0.984--1.06 GeV by CMD-2 at VEPP-2M, the cross section of the reaction e+e- to pi+pi-pi+pi- has been studied. For the first time an interference pattern was observed in the energy dependence of the cross section near the phi meson. The branching ratio of the phi to pi+pi-pi+pi- decay double suppressed by the G-parity and OZI rule is measured Br(phi to pi+pi-pi+pi-) = (3.93 +- 1.74 +- 2.14) \cdot 10^{-6}. The upper limits have been placed for the decays phi to pi+pi-pi+pi-pi0 and phi to eta pi+pi- Br(phi to pi+pi-pi+pi-pi0) < 4.6 \cdot 10^{-6} 90% CL, Br(phi to eta pi+pi-) < 1.8 \cdot 10^{-5} 90% CL.

1 data table

Only statistical errors are presented. The total systematic error is estimated to about 13 PCT.


Study of the Process e+ e- ---> eta gamma in c.m. Energy Range 600-1380 MeV at CMD-2

The CMD-2 collaboration Akhmetshin, R.R. ; Anashkin, E.V. ; Aulchenko, V.M. ; et al.
Phys.Lett.B 509 (2001) 217-226, 2001.
Inspire Record 554522 DOI 10.17182/hepdata.27025

The cross section of the process e+ e- ---> eta gamma has been measured in the 600-1380 MeV c.m. energy range with the CMD-2 detector. The following branching ratios have been determined: B(rho ---> eta gamma) = (3.28 +- 0.37 +- 0.23) 10^{-4}, B(omega ---> eta gamma) = (5.10 +- 0.72 +- 0.34) 10^{-4}, B(phi --> eta gamma) = (1.287 +- 0.013 +- 0.063) 10^{-2}. Evidence for the rho'(1450) ---> eta gamma decay has been obtained for the first time.

1 data table

The measured Born cross section for the ETA GAMMA final state.


Study of the process $e^+e^- \to \pi^+\pi^-\pi^0$ in the energy region $\sqrt[]{s}$ from 0.98 to 1.38 GeV.}

Achasov, M.N. ; Aulchenko, V.M. ; Beloborodov, K.I. ; et al.
Phys.Rev.D 66 (2002) 032001, 2002.
Inspire Record 582183 DOI 10.17182/hepdata.41974

The cross section of the process $e^+e^-\to \pi^+\pi^-\pi^0$ was measured in the Spherical Neutral Detector experiment at the VEPP-2M collider in the energy region $\sqrt[]{s} = 980 \div 1380$ MeV. The measured cross section, together with the $e^+e^-\to \pi^+\pi^-\pi^0$ and $\omega\pi^+\pi^-$ cross sections obtained in other experiments, was analyzed in the framework of the generalized vector meson dominance model. It was found that the experimental data can be described by a sum of $\omega$, $\phi$ mesons and two $\omega^\prime$ and $\omega^{\prime\prime}$ resonances contributions, with masses $m_{\omega^\prime}\sim 1490$,$m_{\omega^{\prime\prime}}\sim 1790$ MeV and widths $\Gamma_{\omega^\prime}\sim 1210$, $\Gamma_{\omega^{\prime\prime}}\sim 560$ MeV. The analysis of the $\pi^+\pi^-$ invariant mass spectra in the energy region $\sqrt[]{s}$ from 1100 to 1380 MeV has shown that for their descriptionone should take into account the $e^+e^-\to\omega\pi^0\to\pi^+\pi^-\pi^0$ mechanism also. The phase between the amplitudes corresponding to the $e^+e^-\to\omega\pi$ and $e^+e^-\to\rho\pi$ intermediate states was measured for the first time. The value of the phase is close to zero and depends on energy.

1 data table

The measured E+ E- --> PI+ PI- PI0 cross section.